1. Field of the Invention
The present invention is directed to a cache technique and more particularly, to a data writing method, a hard disc module and a data writing system.
2. Description of Related Art
At present, mass storage devices that are available in the market can be divided into hard driver disks (HDD) composed of heads and discs and solid state disks (SSD) composed of memories. Generally, a hard driver disk (HDD) has lower production cost and thus, typically has a larger storage capacity than a solid state disk (SSD). However, as for data access speed, the SSD has data access speed several times higher than data access speed of the HDD. Therefore, more and more computer systems adopt hybrid hard disc architecture of the SSHD, in which a HDD serves as a basic data storage space, and the SSD serves as a cache space.
In a conventional hybrid hard disc architecture, a memory of the SSD is commonly formed by a plurality of memory units, and in order to increase data access speed, a single set of data may be divided into a plurality of data segments for simultaneous accessing operation through each of the memory units. Even though such a parallelized access operation can increase the read speed, more fragmented spaces are produced in the memory units since the data is divided and written into different memory units, and each of the memory units merely stores a portion of the data segments. As a result, when the storage space of the memory is insufficient, but a garbage collection operation has to be performed for memory management, the memory has high write amplification factors (WAF) to reduce the lifespan of the SSD.
Accordingly, how to effectively take both the high data access speed and the lifespan of the SSD is a major subject when developing products to the manufacturers in the field.